In general, it is required that the volume of a notebook computer to be more and more compact. Conventionally, an aluminum plate is directly adhered to and presses a microprocessor for dissipating heat of the central processing unit, or a heat pipe is connected to the aluminum plate for radiating. Recently, as in U.S. Pat. Nos. 5781409 and 5832987, a winding chain dissipating block is installed at the pivotal portion between the mainframe seat (or the first seat of an electronic device) and the screen seat (or second seat), which is matched with a heat pipe. Thus, the heat of microprocessor (heat emitting element) in the mainframe seat (first seat) is transferred to the radiating aluminum plate (heat emitting element) within the screen seat (second seat). Thus, the space is used effectively and heat is dissipated efficiently. The winding chain dissipating block is essentially formed by two winding chain dissipating units. The structure of each winding chain dissipating unit 1 is as that shown in FIGS. 1 and 2. The winding chain dissipating unit includes a hollow winding chain outer tube 10. The winding chain outer tube 10 has equal diameter in the axial direction. A heat pipe 11 is further included. One end of the heat pipe 11 has an end connected to a heat emitting element, such as a microprocessor, or connected to a radiating element, such as an aluminum plate. While another end is attached to a winding chain inner tube 12 with an inner diameter approximately equaling to the inner diameter of the winding chain outer tube 10. The winding chain inner tube 12 is pivotally inserted into the winding chain outer tube 10 to be rotated, respectively. Thus, in embodying, two winding chain dissipating units 1 are combined and locked to be placed at the pivotal portion between the mainframe seat (first seat) and the screen seat (second seat) so that the heat pipe 11 of one winding chain dissipating unit 1 is connected to a microprocessor (heat emitting element), while the heat pipe 11 of another winding chain dissipating unit 1 is connected to a heat dissipating aluminum plate (radiating element).
However, in the winding chain dissipating unit 1, the outer diameter of the winding chain inner tube 12 is equal in the whole axial direction and the inner diameter of the winding chain outer tube 10 is also equal in the whole axial direction. Therefore, the two tubes possible slide axially with one another. Moreover, the outer wall of the winding chain inner tube 12 and the inner wall of the winding chain outer tube 10 will possible rub with one another due to the opening and closing actions of the mainframe seat (first seat) and the screen seat (second seat). For a long period of time, the gap therebetween will be enlarged due to wear therebetween. Thus, the inner wall of the winding chain outer tube 10 can not be tightly adhered to the outer wall of the winding chain inner tube 12. That is, the contact area therebetween is reduced gradually so that the heat dissipating efficiency is decreased greatly. Thus, the radiating of the microprocessor is deteriorated.
Therefore, there is an eager demand for an novel winding chain dissipating units, which can overcome the reduction of heat transfer due to the enlarged gap of the winding chain outer tube and the winding chain inner tube from wearing.